Treatment provides additional public health advantages. Anti-retroviral treatment lowers the amount of virus in the body, potentially decreasing the risk of transmission, both among adults and between mothers and their children. New treatment regimens may make an even bigger difference in extending life and holding families together.

But much remains to be done. HIV is a cagey opponent, capable of mutating rapidly and outwitting the drugs that attempt to block it. While to date we still have not developed an effective vaccine, our best minds continue to pursue that noble goal. That is the basic research described in this issue of Lens.

Basic research is also an essential part of our public health defense against emerging viral infections, like SARS, and against the danger posed by potential biological and chemical agents, such as smallpox or anthrax. Research can help us prepare by showing us how viruses damage cellular machinery, and how we might strengthen the body’s immune system against these viral invaders.

We must also look to those areas of the world that have achieved a level of success in fighting the spread of HIV/AIDS and seek to replicate their achievements. Uganda, for example, uses a distinctive approach to AIDS prevention known as ABC: Abstain, Be faithful to one’s partner, and use Condoms. This program combines risk avoidance strategies (through partner reduction) with risk reduction strategies (through prophylactics) and has led to a decline in AIDS prevalence in Uganda, reducing infection rates from 21 percent to 6 percent since 1991.

Thirty years ago, with the success of antibiotics against bacterial infection and vaccines against polio and host of other childhood infections, some experts predicted that medicine had conquered infectious disease. Unfortunately, our experience with AIDS, SARS and antibacterial resistance has shown that our battle against infectious disease is ongoing and ever changing. For instance, even a well-known disease like influenza continues to kill 36,000 people in the United States annually. Given this challenge, we cannot relax or lose our focus; in fact, we must redouble our efforts to prevent, to treat, to understand and to cure.

This issue of Lens includes the latest information about HIV and SARS, the challenges of fending off serious viral illnesses in newborns, and the contributions of scientists like Drs. David Baltimore, Anthony Fauci and Harold Varmus, whose discoveries have added greatly to our understanding of viral infection. The persistence of these investigators in the face of obstacles that would have stopped the less determined should serve as an inspiration to us all.

The immense global challenges posed by the AIDS epidemic seem overwhelming, but working together we can overcome them because we must. That is the political and moral responsibility not only of the scientific and medical community, but also of humanity itself.